PHILADELPHIA (CBS) – SEPTA will spend some $100 million dollars over the next three years to install a new control system for the commuter rail network. The idea is to prevent catastrophic collisions between trains.

Congress mandated the change across the country after a 2008 accident between a commuter train and a freight train killed 25 people in LA. The commuter train’s engineer ran through a red light.

The “positive train control” system will automatically bring trains to a stop if that were to happen here. But SEPTA’s Assistant GM and Chief Engineer Jeffrey Knueppel says compliance will come at a cost.

“We’re very happy to do this project in terms of increasing safety, but we are concerned that we’re getting behind in other areas.”

That is because this will eat up a good chunk of their capital budget, pushing back other work like upgrading bridges and substations.